Enable DMA Remapping Devices by default found in arch/ia64/Kconfig

Help text

Selecting this option will enable a DMAR device at boot time if
one is found. If this option is not selected, DMAR support can
be enabled by passing intel_iommu=on to the kernel. It is
recommended you say N here while the DMAR code remains
experimental.

Enable DMA Remapping Devices by default found in arch/x86/Kconfig

Help text

Selecting this option will enable a DMAR device at boot time if
one is found. If this option is not selected, DMAR support can
be enabled by passing intel_iommu=on to the kernel. It is
recommended you say N here while the DMAR code remains
experimental.

Enable DMA Remapping Devices by default found in drivers/iommu/Kconfig